Remote control system

ABSTRACT

A remote control system for a power operated device having a plurality of positions. Telephone system connected and receiving apparatus at an attended station is combined with telephone system connected receiving and transmitting apparatus at the remote station for enabling an operator at the attended station to advance the device to any of its positions and to receive back information from the remote station indicating to the operator the precise extant position of the device.

United States Patent n91 Hilgedick REMOTE CONTROL SYSTEM [75] Inventor: James R. l-lilgedick, Oakland, Calif. [73] Assignee: Lloyd Bowen, Oakland, Calif.

[22] Filed: Feb. 3, 1971 [21] Appl. No.: 112,123

[52] US. Cl. 340/163 R, 340/171 A [51] Int. Cl. H04m 11/00 [58] Field of Search 340/171 A; 179/2 A, 20 P [56] References Cited UNITED STATES PATENTS 3,123,805 3/1964 Derr 179/2 A X 3,268,662 8/1966 Jackel 179/2 A UX 3,335,227 8/1967 .lackelm 179/2 A 3,383,467 5/1968 New..; 179/2 A 3,529,292 9/1970 Neill 340/163 R 3,531,597 9/1970 Andrewsm. 179/5 P 3,647,971 3/1972 Cushman 179/2 A MULTlPLE CHANNELS-7 1 Jan. 22, 1974 Phinney 340/171 A Primary Examinerl-larold I. Pitts Attorney, Agent, or Firm-Warren, Rubin, Brucker &

Chickering 57 ABSTRACT A remote control system for a power operated device having a plurality of positions. Telephone system connected and receiving apparatus at an attended station is combined with telephone system connected receiving and transmitting apparatus at the remote station for enabling an operator at the attended station to advance the device to any of its positions and to receive back information from the remote station indicating to the operator the precise extant position of the device.

6 Claims, 13 Drawing Figures Pmmfuqmzzmm SHEET 1 or 4 MULTIPLE CHANNELQ INVENTOR.

JAMES R. H ILGE DlC K PATENIED JAN 2 21974 SHEET s [1F 4 k i m mzzzu 32.532

INVENTOR.

JAMES R. H ILGEDICK REMOTE CONTROL SYSTEM The invention relates to communication apparatus for controlling at a distance remotely located machinery, equipment, processes and the like.

In many applications there is a need to control the position or condition of one or a plurality of remotely located operating devices each having a plurality of used terminal positions or conditions, and furthermore to send back from such devices information as to the extant terminal position of each. One suggested use of such apparatus is disclosed in this application in the form of a remotely controlled highway sign which may be located on important well traveled highways leading to and through high mountain pass areas wherein the sign will show the condition of the road, whether open or closed, if closed the point where closed, presence and location and depth of snow, need for chains, motel and hotel accommodations and other .road conditions and travel information, all of which may be required to be updated promptly as conditions change. In such case the attended station may be at or near the summit of the roadway and the remote sign location in the lowland adjacent the mountainous area where appropriate warning as to road conditions may be given and information as above noted most usefully received.

To accomplish the foregoing effectively, economically, dependably, and with complete and accurate feedback information from the remote station of the precise position of the remotely controlled apparatus, are among the objects of the present position.

The invention possesses other objects and features of advantage, some of which of the foregoing will be set forth in the following description of the preferred form of the invention which is illustrated in the drawings accompanying and forming part of this specification. It is to be understood, however, that variations in the showing made by the said drawing and description may be adopted within the scope of the invention as set forth in the claims.

Referring to said drawings:

FIG. 1 is a pictorial representation of part of the remote control system of the present invention.

FIG. 2 is a schematic diagram of another part of the apparatus. I

FIG. 3 is a front elevation of a highway sign depicting one form of application of the present invention.

FIG. 4 is a fragmentary rear elevation of the sign of FIG. 3.

FIG. 5 is a cross sectional view taken substantially on the plane of line 5-5 of FIG. 4.

FIG. 6 is a front elevation on an enlarged scale of one of the sign units.

FIG. 7 is a cross sectional view taken substantially on the plane of line 7--7 of FIG. 6.

FIG. 8 is a schematic diagram of a part of the apparatus seen in FIG. 1.

FIG. 9 is a fragmentary cross sectional view of a portion of one of the sign units.

FIG. 10 is a cross sectional view of the structure shown in FIG. 9 but in a second position.

FIG. .11 is a cross sectional view of the structure shown in FIGS. 9 and 10 but in a third position.

FIG. 12 is a cross sectional view of the structure shown in FIGS. 9-11 in a fourth position.

FIG. 13 is a fragmentary side elevation of the apparatus shown in FIGS. 9-12 as viewed from the plane of line 13-13.

The remote control system of the present invention comprises briefly a power operated device 11 (see motors in FIG. 2 having at least two positions; a remote receiving apparatus 12 having an input 13 and an output switch 14 controlled by a command signal received at input 13, switch 14' being connected in a power control circuit 16 to energize device 11; an attended transmitting apparatus 17 having an output 18 connected to input 13 and a command switch 19 for controlling the generation of a command signal at output 18; a remote transmitting apparatus 21 having an output 22 providing multiple frequency channels and a plurality of switches 23, 24, 25 and 26 for selectively controlling the channel at its output 22, switches 23-26 being mounted for operation by device 11 in its several positions; an attended receiving apparatus 28 having a multiple channel input 29 connected to output 22 and having a plurality of output switches, here shown sixteen in number and identified by reference numerals 31 to 46 which are selectively controlled by the frequency channel received at input 29; and a plurality of indicators 51-66, here sixteen in number corresponding with and being connected to'switches 31-46, and functioning to indicate the extant position of device 11.

As hereinabove noted the remote control system of the present invention is he're'embodied in a highway sign 68 having a face board 69 and four rotary sign members 71, 72, 73 and 74 which may be rotated behind openings in the face board 69 so as to present different messages on the sign members depending upon their rotational position. As best seen in FIG. 7 each of the sign members'is formed as a right angled parallelogram having sides 76, 77, 78 and 79 each carrying an appropriate message and which may be successively moved into position in the adjacent opening or window 80 in the face board 69. Sides 76-79 are here formed of translucent material for illumination by fluorescent lamp tubes 81 mounted interiorly of the sign member. Accordingly in this arrangement 16 different messages may be presented at the face of the sign and four banks 51, S2, S3, and S4 of four switches each are used to sense the appearance at the face of the sign of the 16 signs presented by the four rectangular sign members. Bank S1 is composed of switches 23-26 heretofore referred to and banks S2, S3 and S4 are composed of similar switches 82-93. These 16 switches 23-26 and 82-93 are connected to 16 inputs of remote transmitting apparatus 21 to thereby control the transmission from output 22 of 16 different channels. Attended receiving apparatus 28 is capable of receiving any of these 16 differentfrequency inputs and effecting the closure of output switches 31-46 in accordance with the input frequency received.

In keeping with the above arrangement of four rotary signs,remote receiving apparatus 12 is constructed for multiple channel input at its input 13 for receiving multiple channel command signals from attended transmitting apparatus l7; and is provided with four outputswitches 96,97 and 98 in addition to switch 14 hereinabove identified. These switches 96-98 and 14 are selectively controlled by particular frequency command signals received at input 13. The present apparatus is designed to provide four such command signals from the attended transmitting apparatus 17. The latter is constructed for multiple channel output, with the number of channelsat least equal to the number of actuators 11', and the output channels are selected and controlled by closure of command switches 101, 102, 103 and 19 above identified. Thus, the four switches 101, 102, 103 and 19 will control four remote power operated devices 104, 105, 106 and 11 heretofore identified and which each control the position of one of the four sided sign members 71, 72, 73 and 74 and the 16 combinations thus provided are sensed by switches 23-26 and 82-93, transmitted by apparatus 21 to receiver 28 which then controls the energizing of the 16 indicators 51-66. These indicators may be conveniently provided in the form of electric lamps used to illuminate 16 signs 111-126 provided in a console 109 at the attended station.

Each of the remote power operated devices here comprises the combination of an electric motor 11, 104-106 which is connected to drive one of the rotary sign members 71-74, the latter being journaled for rotation in the support housing 128 of the highway sign 68. As best seen in FIGS. 6 and 7, motor 11 is connected through a gear head 127 to a sprocket 129 enmeshed with a drive chain 130 mounted circumferentially around one of a pair of cylindrical channels 107 and 108 mounted at the opposite ends of each of the rotary sign members 71-74. A plurality of circumferentially spaced rollers 109 carried by housing 128 are mounted to provide coaxial rotary support for channels 107 and 108.

The electric power control circuit for the motors is so arranged that the motors will be energized to start rotation upon closure of switches 19, 101-103 at the attended'station, FIGS. 1 and 8. The latter are here constructed as normally open, push to close, switches and it is desired that energization of the motors be continued after momentary closure of switches 19, 101-103 until the sign members arrive at their next terminal position when automatic opening of the power circuit occurs. Consequently, the operator at the home or attended station may successively move any one of the four remote highway sign members to its successive terminal positions by initiating operation of the, sign member by momentary closure of the appropriate switch 19, 101-103for each successive movement of the sign member. This control circuit comprises briefly a double throw switch 131, see switch bank S1 in FIG. 2; means 132, 133, 134 and 135 (FIGS. 7, 9-11) for sensing the four positions of each of the sign members 71-74, and actuating the double throw switch upon the arrival and departure of the sign member at and from each of its terminal positions. Switch 131 has normally open contacts 136 and 137 which are closed by means 132-135 at each terminal position of the sign member and these contacts 136, 137 are connected in series in the circuit with output switch 14 when the sign member is in each of its terminal positions so that the associated electric motor 11 will be energized to advance the sign member towards its next terminal position. Switch 131 also has a pair of normally closed contacts 137 and 138 opened by means 132-135 at each terminal position and which are connected in parallel across output switch 14 whereby the energizing of the motor will be continued after movement of the sign member from each terminal position and the opening of switch 14 and until arrival of the sign member at its next terminal means 132-135. I

As illustrated in FIG. 6 the four position indicating switches 23-26 and motor control switch 131 for sign member 71 are mounted in a longitudinal array in position for selective engagement by means 131-134 here comprising four arms extending longitudinally from channel 108. These arms are spaced circumferentially from each other at 90 and have cam positions as seen in FIGS. 9-12 for selectively engaging reciprocating actuators on the several switches. Each of arms 131-134 is also provided with a cam portion positioned for engagement with and displacement of the actuator for motor switch 131 so that this double throw switch will be thrown to close and open contacts 136-137 and 137-138 upon arrival of sign member at each of its four terminal positions and to release the actuator for switch 131 upon movement of sign member from its terminal position to provide reversing of the condition of the switch contacts. Additionally, as shown in FIG. 9, member 135 will close switch 26upon movement of one sign face 76-79 into window 80 of the sign. In successive terminal positions of the sign member, as seen in FIGS. 10- 12, arms 133, 134 and 132 will actuate switches 25, 24 and 23 respectively. A similar bank of position switches 82-85, 86-89, 90-93, and similar double throw motor control switches 141, 142 and 143 are provided, as seen in FIG. 2, for the other sign members 72, 73 and 74. Each of the other sign members 72-74 is provided with a set of four switch actuating arms identical in construction to arms 132-135. Only one of the four arms for each of the other signs is illustrated in FIG. 2 where such arms are identified as 134b, 1330 and 135d. The four arms 132-135 in FIGS. 9-12 are for one of the sign units such as sign 71; and four arms 132, 134b, 1330 and 135b shown in FIG. 2 represent one arm from each of the four rotary sign units 7 1-74.

A low voltage relay control circuit is preferably incorporated in the power supply to each of the motors. Four such circuits are used for controlling motors 11, 104-106 from switches 14, 96-98 and double throw switches 131, 141-143. These circuits are identical and a description of one will suffice. High voltage such as the customary volt power supply lines 146 and 147 is applied to the primary 148 of a step-down transformer 149. The low voltage secondary 151 is connected by conductor 152 to one side of a relay coil 153. The other side of the coil is connected by conductor 154 to the movable contact 137 of the double throw switch 131. The low voltage circuit is completed by conductor 156, switch 14 and conductor 157. Normally open relay contacts 158 are closed upon energizing of the relay to complete a high voltage connection to motor 11 via conductors 161, 162 and 163. When the sign member 71 moves to disengage arm 131-134 from switch 131, switch 131 will throw to disengage contacts 136 and 137 and engage contacts 137 and 138. Contact 138 is connected through a second set of normally open relay contacts 164 to conductor 157 by means of conductors 166 and 167 so as to maintain the energizing of motor 11 after switch 131 has thrown. A high speed double acting microswitch is used in the present application which will effect a closing of contacts 137 and 138 prior to opening of contacts 164 thus maintaining the operation of the motor after the microswitch has thrown and switch 14 has been opened. When the sign member arrives at its next terminal. position contacts 137 and 138 will be opened to stop the motor. Accordingly it is only necessary in the present operation that the operator at the attended station momentarily close switch 19, 101-103 until the sign member moves away from its terminal position and microswitch 131 throws.

The transmitters and receivers at the attended and remote stations may be connected by telephone lines, microwave communications or the like. The attended transmitting apparatus 17 as hereinabove noted is constructed to provide a multiple channel output with the number of channels at least equal to the number of electric motors or other remote power operated devices to be controlled, and is adapted for use with a plurality of manually controlled switches 19, 101-103 for selectively controlling the channel at its output. One instrument which may be used for this purpose is produced by American Telephone and Telegraph Company and identified as data set 401E transmitter which has been generally depicted in the drawing. This transmitter while specifically designed to handle business machine equipment has more than enough capacity for present purposes. American Telephone and Telegraph Company data set 401.] may be used for the remote receiving apparatus 12. When these two pieces of equipment are used together as depicted in the drawing, a call initiated from transmitter 17 will be automatically answered by receiver 12 which will initiate an answerback signal to notify the calling station 17 that the receiver 12 is ready for operation. American Telephone and Telegraph Company data set 40 l H may be used for the remote transmitting apparatus 21 and provides more than enough multi-frequency channels to satisfy present conditions; and American Telephone and Telegraph Company data set 40lJ may be. used for the attended receiving apparatus 28. These pieces of equipment are described in Bell System Date Communications, Technical Reference Publications, published by American Telephone and Telegraph Company and entitled Data Sets 40lA and 401E, April 1966, Data Set 4011 Interface Specification, September 1965; and Date Set 401H Interface Specification, March 1969.

Using the above pieces of equipment and telephone line connections, the operation. of the remote control system is as follows. When the operator at the attended station wishes to change one or more of the sign members, he lifts the telephone hand piece 171 of transmitter 17 (data set 40113) and dials the telephone number assigned to remote receiver 12 (data set 401.1). Upon lifting of the hand set of transmitter 17 the conventional dial tone is heard; and upon completion of dialing the customary ringing signal is heard briefly while receiver 12 is energized to go into a data receiving mode. At this point receiver 12 will send a return signal, a high pitched tone, back to transmitter 17 indicating that receiver 12 is in a data receiving mode. Transmitter 17 may then be placed in condition to transmit command signals by .manually raising a data button 172.

The operator will then lift the hand set 173 of receiver 28 (data set 4011) and dial the number assigned to transmitter 21 (data set 4011!). The operator willhear a momentary ringing signal and an answering back of transmitter 21 indicating that ithas been energized. The attendant will then position the data button 1740f instrument 28 so as to place it in its data receiving mode The system is now ready for operation. The operator will now manually close one of the switches 19, 101-103 corresponding with the sign member to be changed. Only a momentary closing of the selected transmitter 21 becomes the calling party" telephone.

Accordingly, after the command has been given to the sign and the sign has changed and transmitted back its position and the attendant hangs up, it is necessry, in a calling party disconnect telephone system, for transmitter 21 to hang up in order to terminate the line connection between transmitter 21 and receiver 28. For this purpose a normally closed relay switch 176 is connected to instrument 21 and functions upon opening to break the line connection between instruments 21 and 28. Control of switch 176 is here effected by an output switch 177 of instrument 12 and which is connected in a series circuit with the transformer secondary 151 and relay coil 178 by conductors 179, 180 and 181. Closing of switch 177 is controlled by one of the operating channels of instrument 12 and which is in turn controlled by an output channel of transmitter 17 energized by closing of a normally open command switch 186 connected to the input of transmitter 17.

Closing of switch 186 will open switch 176, and only a momentary opening of this latter switch is required to disconnect the telephone line connection between transmitter 21 and receiver 28. Accordingly after all signals have been transmitted and return and read as requested, the two hand pieces of instrument 17 and 28 are hung up" by returning them to their respective cradles and the two telephone lines employed for the transmission and return of information are disconnected; Thus, with the use of the equipment as described, regular telephone lines may be used between the attended and remote stations and the use of the lines confined to the time when command and return signals are actually being transmitted.

I claim:

1. A remote control system comprising:

a remote power operated device having at least two' positions;

a plurality of remote switches one for each of said positions mounted for operation by said device in said positions;

a remote telephone system connected apparatus;

an attended telephone system connected apparatus adapted for system-wide selective connection to said remote apparatus and having:

a. an output and a command switch for controlling the generation of a command signal at said output,

b. a receiving means having multiple frequency signal channel input and a plurality of second outputs selectively controlled by the frequency channel received at its input;

a. plurality of indicators connected to said second outputs;

said remote apparatus having:

a. an input connected to receive said command signal and an output controlled thereby, said output being connected to energize said device,

b. transmitting means having a pluralityof inputs connected to said switches and an output providing multiple frequency channels controlled thereby and connected to said attended apparatus input whereby theextant position of said device will be shown by one of said indicators.

2. A remote control system as defined in claim 1:

said remote power operated device comprising a plurality of electric actuators and parts driven thereby and said remote switches being mounted for sensing the positions of each part and being connected to said remote transmitting means for selectively controlling the channel at its output;

said remote apparatus including receiving means having a multiple channel input with the number of channels being at least equal to the number of said actuators and for receivingmultiple channel command signals, and a plurality of output switches equal in number to said actuators and selectively controlled by said signals and being connected to energize said actuators;

said attended apparatus including transmitting means having a multiple channel output and a plurality of manually controlled command switches for selectively controlling the channel at said last named output with the number of last named channels and switches being at least equal to the number of said actuators;

said remote transmitting means and said attended receiving means having a multiplicity of channels equal in number to the total number of positions of said parts; and

said indicators being connected and functioning to indicate the extant position of each of said parts.

3. A system as defined in claim 2, said actuators and parts comprising electric motors and rotary parts driven thereby and said remote switches being positioned for engagement and actuation by said parts to sense the angular positions thereof, said remote switches being connected to de-energize said motors in predetermined positions of said parts.

4. A system as defined in claim 1:

said remote receiving output including an output switch, an electric power control circuit connected for energizing said device for movement to at least two terminal positions and being connected to said last named switch;

a double throw switch;

means sensing the position of said device and actuating said double throw switch upon the arrival and departure of said device at and from each of said terminal positions;

said double throw switch having normally open contacts closed by said position sensing means at each terminal position and connected in series in said circuit whereby upon closing of said output switch when said device is in each of its terminal positions said device will be energized to advance toward its next terminal position; and

said double throw switch having normally closed contacts opened by said position sensing means at each terminal position and connected in parallel across said output switch whereby the energizing of said device will be continued after movement of said device from each terminal position and the opening of said output switch until arrival of said device at its next terminal position.

5. A system as defined in claim 4:

said power operated device comprising an electric motor and rotary part driven thereby to a plurality of circumferentially spaced terminal positions;

the plurality of remote switches being equal in number to the number of said terminal positions; and

said position sensing means comprising a plurality of actuator members equal in number to the number of said terminal positions carried by said part and actuating one of said last named switches and said double throw switch in each of said terminal positions.

6. A remotely controlled sign comprising:

an attended transmitting apparatus having an output providing multiple frequency channels;

a plurality of manually controlled switches connected to said apparatus for selecting the frequency channel at said output;

a remote receiving apparatus having a multiple frequency channel input connected to said output and having a plurality of output switches selectively controlled by the frequency channel received at said input;

a sign having a plurality of electric motor driven sign members connected to said output switches and selectively energized thereby; said sign members having a plurality of sign messages thereon individually presented in predetermined positions of said members;

a remote transmitting apparatus having an output providing multiple frequency channels and a plurality of switches for selectively controlling the channel transmitted, said last named switches being mounted for operation by said sign members in said predetermined positions thereof;

an attended receiving apparatus having a multiple frequency channel input connected to said output of said remote transmitting apparatus and having a plurality of output switches selectively controlled by the frequency channel received at its said input; and

a plurality of indicators connected to said last named switches and functioning to indicate the extant positions of said sign members.

I! i l UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent 3.7874811 jannamww Inventor(s) JAMEQ 12 HTLGEDTPK It is certified that error appears in the above-identified patent and that said Letters Patent are hereby corrected as shown below:

Abstract, line 3, after "nected" add --transmitting-.

Column 5, line 41, change "1966," to --1966;--.

Column 5, .line 43, change "Date" to --Data.

Signed and sealed this 3rd day of September 1974.

' [SEALl Attestt :McCOY M. GIBSON, JR. 0. MARSHALL DANN Attesting Officer Commissioner of Patents 

1. A remote control system comprising: a remote power operated device having at least two positions; a plurality of remote switches one for each of said positions mounted for operation by said device in said positions; a remote telephone system connected apparatus; an attended telephone system connected apparatus adapted for system-wide selective connection to said remote apparatus and having: a. an output and a command switch for controlling the generation of a command signal at said output, b. a receiving means having multiple frequency signal channel input and a plurality of second outputs selectively controlled by the frequency channel received at its input; a plurality of indicators connected to said second outputs; said remote apparatus having: a. an input connected to receive said command signal and an output controlled thereby, said output being connected to energize said device, b. transmitting means having a plurality of inputs connected to said switches and an output providing multiple frequency channels controlled thereby and connected to said attended apparatus input whereby the extant position of said device will be shown by one of said indicators.
 2. A remote control system as defined in claim 1: said remote power operated device comprising a plurality of electric actuators and parts driven thereby and said remote switches being mounted for sensing the positions of each part and being connected to said remote transmitting means for selectively controlling the channel at its output; said remote apparatus including receiving means having a multiple channel input with the number of channels being at least equal to the number of said actuators and for receiving multiple channel command signals, and a plurality of output switches equal in number to said actuators and selectively controlled by said signals and being connected to energize said actuators; said attended apparatus including transmitting means having a multiple channel output and a plurality of manually controlled command switches for selectively controlling the channel at said last named output with the number of last named channels and switches being at least equal to the number of said actuators; said remote transmitting means and said attended receiving means having a multiplicity of channels equal in number to the total number of positions of said parts; and said indicators being connected and functioning to indicate the extant position of each of said parts.
 3. A system as defined in claim 2, said actuators and parts comprising electric motors and rotary parts driven thereby and said remote switches being positioned for engagement and actuation by said parts to sense the angular positions thereof, said remote switches being connected to de-energize said motors in predetermined positions of said parts.
 4. A system as defined in claim 1: said remote receiving output including an output switch, an electric power control circuit connected for energizing said device for movement to at least two terminal positions and being connected to said last named switch; a double throw switch; means sensing the position of said device and actuating said double throw switch upon the arrival and departure of said device at and from each of said terminal positions; said double throw switch having normally open contacts closed by said position sensing means at each terminal position and connected in series in said circuit whereby upon closing of said output switch when said device is in each of its terminal positions said device will be energized to advance toward its next terminal position; and said double throw switch having normally closed contacts opened by said position sensing means at each terminal position and connected in parallel across said output switch whereby the energizing of said device will be continued after movement of said device from each terminal position and the opening of said output switch until arrival of said device at its next terminal position.
 5. A system as defined in claim 4: said power operated device comprising an electric motor and rotary part driven thereby to a plurality of circumferentially spaced terminal positions; the plurality of remote switches being equal in number to the number of said terminal positions; and said position sensing means comprising a plurality of actuator members equal in number to the number of said terminal positions carried by said part and actuating one of said last named switches and said double throw switch in each of said terminal positions.
 6. A remotely controlled sign comprising: an attended transmitting apparatus having an output providing multiple frequency channels; a plurality of manually controlled switches connected to said apparatus for selecting the frequency channel at said output; a remote receiving apparatus having a multiple frequency channel input connected to said output and having a plurality of output switches selectively controlled by the frequency channel received at said input; a sign having a plurality of electric motor driven sign members connected to said output switches and selectively energized thereby; said sign members having a plurality of sign messages thereon individually presented in predetermined positions of said members; a remote transmitting apparatus having an output providing multiple frequency channels and a plurality of switches for selectively controlling the channel transmitted, said last named switches being mounted for operation by said sign members in said predetermined positions thereof; an attended receiving apparatus having a multiple frequency channel input connected to said output of said remote transmitting apparatus and having a plurality of output switches selectively controlled by the frequency channel received at its said input; and a plurality of indicators connected to said last named switches and functioning to indicate the extant positions of said sign members. 